Every February, visitors to Yosemite National Park in California have a chance of catching an amazing sight: a mountain waterfall that looks like flowing lava. This year, the view was particularly spectacular.
The phenomenon, called a firefall, happens only under certain conditions. It requires heavy snow, followed by warm temperatures to melt it into a flowing waterfall. Then, on a clear day, the sun has to hit the water at just the right angle.
It’s rare for all those factors to line up. If they do, the waterfall lights up for about 10 minutes—until the angle of the sun changes. Tourists flock to Yosemite every winter hoping to catch a glimpse.